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Did you know, the first computer was as big as your classroom! 60 years ago,computers were very big, costly and used lot of electricity. The processors of the first computers were made using something called'vacuum tubes' - which used tubes in which electrons were moving.  

Did you know, the first computer was as big as your classroom! 60 years ago,computers were very big, costly and used lot of electricity. The processors of the first computers were made using something called'vacuum tubes' - which used tubes in which electrons were moving.  

Punch cards were an input method. After the vacuum tubes, came the transistors

Punch cards were an input method. After the vacuum tubes, came the transistors

which could turn electricity in a circuit 'on' or 'off'.This turning 'on'  

which could turn electricity in a circuit 'on' or 'off'.This turning 'on'  

and 'off' could be used to instruct computers to do calculations.[[Image:IntroductionPart3_html_797aeff2.png|thumb| right]]

and 'off' could be used to instruct computers to do calculations.[[Image:Introduction-Part3_html_797aeff2.png|thumb| right]]